As for most, I think, speaking and listening are hardest for me. Since I'm not quite fluent in a second language yet, most native speakers speak more quickly than my ears can keep up with! I'm a visual learner, and speaking requires me to visualize in my head, which is not something I've perfected yet. Try speaking to me in Spanish and you'll see me with my eyes rolled up trying to see what's going on inside my brain! I find writing to be the easiest, but probably because I make many many mistakes without realizing it. Reading is easier for me, but not quite as easy as writing, sometimes I take the words too literally and they don't make sense to me. I tend to translate directly.